The present invention relates to a motor-vehicle door latch. More particularly this invention concerns a power closer that shifts a door bolt to pull in a door after it has been latched shut.
A motor vehicle door is normally provided on its outer edge opposite its hinged edge with a latch having an element typically formed as a fork engageable around a bolt projecting from a door post. The fork can retain the bolt in the latch housing to hold the door closed, and can slide or pivot to release the bolt and allow the door to be opened. On closing the fork is automatically engaged and latches the door which engages in the door opening against an annular seal typically carried on the vehicle body.
In today""s vehicles it is important that the door be as tightly closed as possible, in order to reduce drafts and noise. Thus the door should, in the closed position, exert the maximum possible compression on the door seal. This effect is most simply achieved by simply only letting the latch engage in its end position when the door is forcibly closed, requiring the user to pull or push it solidly to.
Better vehicles incorporate a power-closing system which, once the fork has latched around the bolt, displace the bolt inward through a short extra stroke that ensures that the door will be tightly closed. The system is also normally set to move the bolt outward through its stroke when one of the latches is initially actuated to open the door. In this manner the user is not burdened with having to close a door very tightly, or deal with opening a very tightly closed door. In practice such a system allows a door to be pulled much more tightly closed than could normally be expected by a standard system. These arrangements are particularly usable on the trunk door as they allow the user to merely push the door to and thereafter it will fully close by its own automatic operation.
These power closing systems work various ways. In U.S. patent application Ser. No. 09/338,036 filed Jun. 22, 1999 and in German patent document 4,210,893 published Oct. 7, 1993 for P. Szablewski the bolt is mounted slightly eccentrically on a rotary mount that is driven by an electric motor through a step-down transmission. These systems have the disadvantage that the bolt moves the same distance crosswise to the closing direction as parallel to this direction, so that the door will move vertically somewhat as it closes. It is preferred that this movement be substantially only in a direction perpendicular to the seal so that the door fits snugly without undue wear to the seal and other parts.
In German patent 3,721,963 issued Oct. 13, 1988 to K. Raffelseifer the bolt is mounted on a pair of crank arms and is pushed by a lever operated by an eccentric drive. German patent document 3,401,842 published Aug. 1, 1985 describes a system where the bolt is mounted on a carriage fixed to a flexible element that is payed in and out to advance and retract it. The bolt in German patent document 4,410,712 published Oct. 13, 1994 for D. Sack is mounted on a carriage that is carried on a threaded spindle fixed in the door post so that rotation of the spindle advances and retracts the bolt carriage. All of these systems are relatively expensive and some are quite bulky. As the item is intended for mass production and must have a long service life, it must be as rugged and simple as possible.
It is therefore an object of the present invention to provide an improved power closer for a motor-vehicle door latch.
Another object is the provision of such an improved power closer for a motor-vehicle door latch which overcomes the above-given disadvantages, that is which is of very simple and robust construction.
A further object is to provide such a simple and robust power closer whose bolt moves in a generally straight line.
A power-closing motor-vehicle latch-bolt assembly has according to the invention a housing, an elongated rocker having inner and outer ends, and a pivot at the inner end connecting the rocker to the housing for pivoting about an axis passing through the inner end. A drive engageable with the outer end pivots the rocker about the axis. A door bolt fixed to and projecting from, the rocker is engageable with a door-mounted fork. The bolt projects from the rocker between the ends thereof.
This structure is extremely simple and rugged. Nonetheless the bolt moves in an essentially straight line as the rocker pivots so there will be no significant vertical movement of the door, unlock the prior art systems where the bolt pivoted about an axis lying within its outline so that the vertical component of its travel was the same as its horizontal component.
The housing is formed with a slot through which the bolt projects and along which the bolt travels when the rocker is pivoted about the axis. Furthermore the housing is provided with a guide pin extending parallel to the axis offset from the pivot. The rocker is formed with an arcuate slot through which the guide pin extends and along which it travels when the rocker is pivoted about the axis.
The bolt according to the invention is between the guide pin and the pivot. In addition the guide pin has an enlarged head and the rocker lying between the enlarged head and the housing where the pin is fixed. A spring urges the rocker pivotally into an outer end position and against the drive. This spring engages the outer end of the rocker.
The drive includes a motor having an output, a wheel rotatable about a wheel axis parallel to the pivot axis, an eccentric element carried on the wheel and engageable radially of the wheel axis with the outer end of the rocker, and step-down gearing between the motor output and the wheel. The step-down gearing includes at least one worm gear meshing with a toothed periphery of the wheel. A switch actuatable by the rocker in an end position thereof reports the position of the door to an onboard computer.